Question
A random sample of n 1 =20winter days in Denver gave a sample mean pollution index x 1 =43. Previous studies show that 1 =11.
A random sample ofn1=20winter days in Denver gave a sample mean pollution indexx1=43. Previous studies show that1=11. For Englewood (a suburb of Denver), a random sample ofn2=12winter days gave a sample mean pollution index ofx2=36. Previous studies show that2=13. Assume the pollution index is normally distributed in both Englewood and Denver. Do these data indicate that the mean population pollution index of Englewood is different (either way) from that of Denver in the winter? Use a 1% level of significance.
What is the value of the sample test statistic? (Test the difference12. Round your answer to two decimal places.)
(c)
Find (or estimate) theP-value. (Round your answer to four decimal places.)
Q2
A Michigan study concerning preference for outdoor activities used a questionnaire with a six-point Likert-type response in which 1 designated "not important" and 6 designated "extremely important." A random sample ofn1=48adults were asked about fishing as an outdoor activity. The mean response wasx1=4.9. Another random sample ofn2=50adults were asked about camping as an outdoor activity. For this group, the mean response wasx2=5.5. From previous studies, it is known that1=1.5and2=1.2. Does this indicate a difference (either way) regarding preference for camping versus preference for fishing as an outdoor activity? Use a 5% level of significance.
Note: A Likert scale usually has to do with approval of or agreement with a statement in a questionnaire. For example, respondents are asked to indicate whether they "strongly agree," "agree," "disagree," or "strongly disagree" with the statement.
a) What is the value of the sample test statistic? (Test the difference12. Round your answer to two decimal places.)
b) Find (or estimate) theP-value. (Round your answer to four decimal places.)
Q3
A random sample ofn1= 10 regions in New England gave the following violent crime rates (per million population).
x1:New England Crime Rate3.53.94.24.13.34.11.84.82.93.1
Another random sample ofn2= 12 regions in the Rocky Mountain states gave the following violent crime rates (per million population).
x2:Rocky Mountain Crime Rate3.74.14.75.53.34.83.52.43.13.55.22.8
Assume that the crime rate distribution is approximately normal in both regions.
(a)
Use a calculator to calculatex1,s1,x2, ands2. (Round your answers to four decimal places.)
x1=
s1=
x2=
s2=
What is the value of the sample test statistic? (Test the difference12. Round your answer to three decimal places.)
Q4
In this problem, assume that the distribution of differences is approximately normal.Note: For degrees of freedomd.f. not in the Student'sttable, use the closestd.f. that issmaller. In some situations, this choice ofd.f. may increase theP-value by a small amount and therefore produce a slightly more "conservative" answer.
Are America's top chief executive officers (CEOs) really worth all that money? One way to answer this question is to look at rowB, the annual company percentage increase in revenue, versus rowA, the CEO's annual percentage salary increase in that same company. Suppose a random sample of companies yielded the following data:
B: Percent increase for company
24 25 25 18 6 4 21 37
A: Percent increase for CEO
21 23 24 14 4 19 15 30
Do these data indicate that the population mean percentage increase in corporate revenue (rowB) is different from the population mean percentage increase in CEO salary? Use a 5% level of significance. (Letd=BA.)
What is the value of the sample test statistic? (Round your answer to three decimal places.)
Q5
In this problem, assume that the distribution of differences is approximately normal.Note: For degrees of freedomd.f. not in the Student'sttable, use the closestd.f. that issmaller. In some situations, this choice ofd.f. may increase theP-value by a small amount and therefore produce a slightly more "conservative" answer.
At five weather stations on Trail Ridge Road in Rocky Mountain National Park, the peak wind gusts (in miles per hour) for January and April are recorded below.
Weather Station 1 2 3 4 5
January. 135 120 126 64 78
April 108 115 100 88 61
Does this information indicate that the peak wind gusts are higher in January than in April? Use= 0.01. (Letd= JanuaryApril.)
What is the value of the sample test statistic? (Round your answer to three decimal places.)
Q6
In this problem, assume that the distribution of differences is approximately normal.Note: For degrees of freedom d.f. not in the Student'st-table, use the closest d.f. that issmaller. In some situations, this choice of d.f. may increase theP-value by a small amount and therefore produce a slightly more "conservative" answer.
In environmental studies, sex ratios are of great importance. Wolf society, packs, and ecology have been studied extensively at different locations in the U.S. and foreign countries. Sex ratios for eight study sites in northern Europe are shown below.
Location of Wolf Pack%
Males (Winter)% Males (Summer)
Finland76 57
Finland51 54
Finland71 55
Lapland55 48
Lapland64 55
Russia50 50
Russia41 50
Russia55 45
What is the value of the sample test statistic? (Round your answer to three decimal places.)
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